<template>
  <div class="todo-footer" v-show="total">
    <label>
      <input type="checkbox" :checked="isAll" @click="checkAll"/>全选
    </label>
    <span>
          <span>已完成 {{doneTotal}}</span> / 全部 {{total}}
    </span>
    <button class="btn btn-danger" @click="clearAll">清除已完成任务</button>
  </div>
</template>

<script>
export default {
  name: "MyFooter",
  props:['todos','checkAllTodo','clearAllTodo'],
  computed:{
    doneTotal(){
      // 使用数组reduce方法
      return this.todos.reduce((pre,todo)=>{
        return pre + (todo.done ? 1:0);
      },0)
    },
    // 计算总代办事项的个数
    total(){
      return this.todos.length;
    },
    // 是否全部完成
    isAll(){
      return this.total === this.doneTotal && this.total>0
    }
  },
  methods:{
    // 全选
    checkAll(e){
      this.checkAllTodo(e.target.checked);
    },
    // 清楚已完成任务
    clearAll(){
      this.clearAllTodo();
    }
  }
}
</script>

<style scoped>
.todo-footer{
  height: 40px;
  line-height: 40px;
  padding-left: 6px;
  margin-top: 5px;
}
.todo-footer label{
  display: inline-block;
  margin-right: 20px;
  cursor:pointer;
}
.todo-footer label input{
  position: relative;
  top: -1px;
  vertical-align: middle;
  margin-right: 5px;
}
.todo-footer button{
  float: right;
  margin-top: 5px;
}
</style>